1. Field of the Invention
This invention pertains generally to the field of cockpit indicators or display units that provide flight information to the pilot or flight crew of an aircraft, and more particularly to synthetic vision systems or enhanced vision systems.
2. Description of the Related Art
Modern avionics systems employ Head-Down Display (“HDD”) and Head-Up Display (“HUD”) systems for providing tactical and/or strategic flight information to the pilot. In an HDD system, tactical and/or strategic flight displays are mounted in the cockpit instrument panel directly in front of the pilot and below windshield level. To view the presentation of information on a display unit of an HDD system, a pilot must look down into the cockpit, causing him or her to take his or her eyes from the outside scene in front of the aircraft. In a HUD system, a HUD unit is mounted in front of the pilot at windshield level and is directly in the pilot's field of vision. The HUD system is advantageous because the display is transparent allowing the pilot to keep his or her eyes “outside the cockpit” while the display unit provides tactical flight information to the pilot.
Modern avionics systems may employ Synthetic Vision Systems (singularly, “SVS”) and Enhanced Vision Systems (singularly, “EVS”) for displaying terrain information to both HDD and HUD systems. The SVS and EVS systems are advantageous because they present terrain information and objects of a scene outside the aircraft to the pilot. For example, an airport, airport runways, navigation aids, and obstacles may be objects displayed by an SVS that can increase a pilot's Situational Awareness and potentially provide a means for navigation. While the presentation of this information is advantageous to the pilot, there are times when the depiction of object information could obstruct or obscure a pilot's view of tactical flight information or symbology simultaneously depicted. Airports can vary in size and can be, at times, difficult to locate and identify with the simultaneous display of flight symbology and a three-dimensional perspective of terrain. This difficulty of locating and identifying is especially acute when an airport or another object is relatively distant from the current position of the aircraft and appears relatively small due to the three-dimensional minification of distant objects.
To aid in locating distant objects, location highlighters may be employed such as those disclosed by Yum et al in U.S. Pat. No. 8,094,188 entitled “System, Apparatus, and Method for Enhancing the Image Presented on an Aircraft Display Unit through Location Highlighters,” which is incorporated by reference herein in its entirety. Examples of location highlighters are shown as items 10 and 20 in FIGS. 1A and 1B.
To aid in identifying distant objects, location markers may be employed such as those disclosed by Frank et al in U.S. Pat. No. 8,099,234 entitled “System, Apparatus, and Method for Generating Location Information on an Aircraft Display Unit using Location Markers,” which is incorporated by reference herein in its entirety. Examples of location highlighters are shown as items 30 through 60 in FIGS. 2A and 2B.
Location highlighters not only aid in locating distant objects but also aid in highlighting other invisible objects such as, but not limited to, waypoints and flight path boundaries as disclosed by Chiew et al in U.S. Pat. No. 7,965,202, which is incorporated by reference herein in its entirety. Examples of location highlighters employed for invisible objects are shown as items 70 through 90 in FIGS. 3A and 3B.
Although location highlighters and location markers aid in locating and identifying distant objects, the presentation of multiple location highlighters and/or multiple location markers within the same image could present too much information and create pilot confusion which could lead to a loss of situational awareness.